Vertical Keystone correction. Is this really terrible?

[ramanjogi]

I own Epson TW6000 1080P projector and installed it on the wall in a custom made shelf. The projector rest 3 feet below the ceiling and my screen fixed at 1.5 feet below the ceiling. To assemble the image fill the screen I have tilted the projector about 25 degree and use vertical Keystone correction up to -27. I have watched movies for 200 hours and very happy with the outcome . By no means I recognize the drawback of keystone correction till yesterday. One of my friend visited me and when he saw the setup he said I am loosing almost 50% of sharpness due to the keystone correction. Because I am a videophile , my friend turn out well in seeding the uncertainty and confusion in my mind concerning the negative aspect of keystone correction. My question is :
1- does 1080P projector loss resolution and brightness when use Vertical keystone correction?
2- Till now I get pleasure from all the details of bluray but soon after realizing the speculative disadvantage of keystone correction I find myself mystified and at the moment not able to enjoy the movies.
Shall I change the position of my Projector ?

 

[dlkanth]

key stone correction has very little to with ur sharpness, it only adjusts ur image vertical tilts. make ur key stone to zero. centre the image , use the key stone to fine tune only.. sharpness got a lot of things to chk, focus/cable/source. picture modes in projector..

 

[ramanjogi]

key stone correction has very little to with ur sharpness, it only adjusts ur image vertical tilts. make ur key stone to zero. centre the image , use the key stone to fine tune only.. sharpness got a lot of things to chk, focus/cable/source. picture modes in projector..

When I shift the Vertical keystone to zero position the image converted into trapezoid. If I keep the projector parallel to the screen without tilting it than the image will throw half way up to the screen.

 

[goyal.sanchit]

Thats the problem with high end audio and video. When you get into the technicalities you stop enjoying the movie and music. I have a home theatre and while my brother and every one else enjoy movies I am always thinking the projector should be better caliberated or the audio needs to be fine tuned!

Sometimes knowledge is evil.

I use a vertical keystone correction of -3 and the effect is negligible on picture quality. -27 is a bit too much but if you were enjoying the picture quality before you should not worry much.

 

[anm]

When I shift the Vertical keystone to zero position the image converted into trapezoid. If I keep the projector parallel to the screen without tilting it than the image will throw half way up to the screen.

do you notice sharpness difference between correct and uncorrected images? If yes, then keystone is an issue, else maybe a little more focus needed.

Once that question is behind you, we can look at more possible solutions to fix it.

 

[anm]

deleted - wrong post

 

[ontherocks]

I don't think keystone correction has anything to do with sharpness.
Try it yourself.
Keep the projector=0 and keystone=0. Play some 1080p video. Let half of the image go to the ceiling. Look for a scene containing "something" with intricate details in the lower half that's projected on the screen. Pause it there. Take a photograph of that "something" (not the whole screen) with a camera in a fixed position.

Next, repeat this with projector=25 and keystone=-27. Compare the two images side by side.

 

[ramanjogi]

I don't think keystone correction has anything to do with sharpness.
Try it yourself.
Keep the projector=0 and keystone=0. Play some 1080p video. Let half of the image go to the ceiling. Look for a scene containing "something" with intricate details in the lower half that's projected on the screen. Pause it there. Take a photograph of that "something" (not the whole screen) with a camera in a fixed position.

Next, repeat this with projector=25 and keystone=-27. Compare the two images side by side.

This afternoon I place the projector inverted in the book shelf and set the image as ceiling mount . while keeping the projector parallel to the screen I notice the screen fill is 3/4th and with little bit of adjustment +4 keystone make the video perfect.
As per your suggestion I found insignificant variation between 0 to +5 or -10 but there is substantial amount of distortion when I run the professional photo and HD calibration video.
Anyway I have decided to keep the new setup for peace of my mind.

Thanks friends

 

[ontherocks]

Could you give some more details about the calibration video

 

[ramanjogi]

Could you give some more details about the calibration video

Please check this URL avsforum.com/avs-vb/showthread.php?t=948496